MRI imaging of displaced meniscal tears: Report of a case highlighting new potential pitfalls of the MRI signs

Abstract

Magnetic resonance imaging (MRI) has been found to be an excellent imaging tool for meniscal injuries. Various MRI signs have been described to detect displaced meniscal injuries, specifically the bucket-handle tears. Although these signs are quite helpful in diagnosing meniscal tears, various pitfalls have also been reported for these signs. Double anterior cruciate ligament (ACL) sign refers to presence of a linear hypointense soft tissue anterior to the ACL, which represented the flipped bucket-handle tear of the meniscus. Disproportional posterior horn and flipped meniscus signs represent asymmetrically thickened horns of the menisci due to overlying displaced meniscal fragments. We report a case wherein MRI of the knee showed tear and displacement of the medial patellofemoral ligament (MPFL) and vastus medialis complex, medial collateral ligament (MCL), and posterior cruciate ligament (PCL) mimicking these signs. To our knowledge, internally displaced MPFL and MCLs have not been described as mimics for displaced meniscal fragments.

The treatment of bucket handle meniscus tear using “the pulling suture technique”: A new surgical technique

“…For example, an anterior displacement of the torn meniscus could appear parallel to the posterior cruciate ligament (PCL), called double PCL sign, although when the anteriorly displaced fragment lies superior to the native horn, it is a flipped meniscus sign. Absence bow tie sign is seen on the sagittal cut when one or both meniscal bodies can't be visualized [12] .…”